Motor-driven fluid distribution system



Oct. 6, 1953 e. A. WAHLMARK MOTOR-DRIVEN FLUID DISTRIBUTION SYSTEM 5 Sheets-Sheet 1 Filed May 29, 1950 cbvLkm/ (B-"o a s Oct. 6, 1953 G. A'. WAHLMARK MOTOR-DRIVEN FLUID DISTRIBUTION SYSTEM 3 Sheets-Sheet 2 Filed May 29, 1950 Oct. 6, 1953 e. A. WAHLMARK 2,654,323

MOTOR-DRIVEN FLUID DISTRIBUTION SYSTEM Filed May 29, 1950 3 Sheets-Sheet I5 Fig. 3 showing modified -forms of the Patented Oct. 6, 1953 UNITED STATES "PATENT OFFICE "MOTOR-DRIVEN FLUID DISTRIBUTION SYSTEM '7 Claims.

This invention .relates to fluid distributing sysitems of the type in which fluid is placed under pressure by operation of an electric motor driven pump and is admitted to a point of use such fas aspray nozzle when the pressure in the pump outlet has attained a predetermined value. Systems of this character are commonly used in conjunction with oil burners .towhich air "for Zcdmbustion is supplied 'by a blower driven by the pump motor.

One object of the invention is to provide a fluid distributing system of the above char- [acter .in which the admission of pressure fluid, to the point of use is delayed in a novel manner .unt'il the pump driving motor has attained .nearly I the accompanying drawings, in which Figure 1 is a schematic view of the primary elements of an oil burner incorporating a fluid distribution system embodying the novel features of the present invention.

Fig. '2 is an elevational view of the improved pump and valve unit 'broken away to show part of the .fiuid distributing system in section.

Fig. 3 is an enlarged fragmentary .sectional view of a part of Fig. 2.

.Fig. a is a perspective view of the valve ,di- 'aphragm. v

Fig. 5 is a section taken along the 'line .5-7-5 of "2.

Fig. 6 is a schematic view of the main operating parts and fluid passages.

Figs. "7 and ;8 are sectional views similar to automatic "valve.

The :invention is especially adapted for use in a pump unit for supplying fuel oil at a .de-

sired pressure "to the nozzle 1'0 of an oil burner having a blower H for delivering air to the combustion chamber and driven by an electric motor 1 2 which is respectively energized and -deenergized to start and stop the burner. The

motor also drives a pump l3 which 'draws oil from a -supply pipe M and a tank 14*. In order "2'5. valve .above referred to are combined in a mul- .motor and which meshes with the internal teeth of -a ring gear 1.! whose outer periphery is journaled v eccentrica'lly of the pinion in a cylindrical bearing it formed by a casing l9 closed :at opposite ends by fiat walls abutting against the ends of the gears. A crescent shaped 'ri-b 20 separates the teeth of the two gears on one side so as to define inlet and outlet pockets fland '22 at opposite ends of the crescent. The inlet communicates with a passage 23 into which ifuel oil from the pipe [4 flows after passing through a suitable filter 24 disposed within a chamber The .pump, the filter, and the automatic tiple part housingzfi to form a compact unit which may be mounted through the medium of a flange 21.

In a system of the above character, it is desirable, in order to insure complete atomization and combustion of the fuel oil during start- Lingand stopping of theburner, not only to open and close the admission valve .quickly after energization .and deenergization of the pump motor, but also to delay the admission of the oil until the motor has reached nearly its full speed and the blower has thus attained r1111 efficiency and is supplying an ample volume of air to burn all of the oil initially sprayed from the ,nozzle. In accordance with the present invention, such .delay is achieved by the novel coaction between a continuously acting by-pass valve v5.! and an automatic pressure responsive cut-oil valve 29,

the former .being of fixed size such as to by-pass the major portion of the fluid delivered by the pump while the latter operates to passfiuid to the burner nozzle only after the pump outlet pressure ,fnas attained a value, for example 120 p. s. i., considerably above the desired normal operating pressure, for example .1100 p. s. 1., at which the valve will be .held open by application of the pump outlet pressure after the .valve has once become open;

Referring now to the preferred embodiment of the invention shown in Figs. 1 to 18, the pump outlet 22 communicates with a'passa-ge '28 leading to a main admission and cut-off valve "29 having-a movable member '30 which is *normally urged in the valve closing direction *by means such as a spring 3I,-the force of which is opposed by the outlet pressure acting on one area of the member when the *valve "is closed and "on a larger area while the valve "is open.

to achieve quick starting of the oil burner, "it "is. desirable to employ a pump havinga capacity The pump shown herein comprises a pinion, ["5 which is fast on a shaft f6 coupled to'the -rib 33 is 'on the outer end of a into a hole .in the housing.

The va-lve 29 is formed in part byva fiat seat 32 flat the end of an annular rib 33 disposed horizontally and projecting into :a surrounding recess it'd-formed 'in one side of the housing -26. The plug 35 pressed "The passage "28 connects the pump outletwith that portion "of "the recess ",34 surrounding the :valve rib 33 while the annular port '31 defined by the v:rib communicates with apassajge 38 opening outwardly "from "the housing '26 andconnectedto sn pe 39'ieading to the nozzle 10.

Cooperating with the seat 32 to form the valve 29 is a surface which is formed herein on a diaphragm 49 constituting a covering for the member 30 which in the present instance comprises a flat circular rigid disk fitting loosely in a circular recess 4| in a cap 42 which is clamped by screws 43 against the housin 26 to cover the valve recess. On the side facing the valve recess, the disk 30 lies against the diaphragm which is composed of thin flexible oil resistant material such as firm synthetic rubber preferably having a peripheral flange 40 which is larger than the 7 disk proper and seated in a groove in the cap 42 by which the periphery of the diaphragm is clamped securely against the housing 26 and the cap 42, thus sealin the valve recess 34. The diaphragm is undercut to form a groove 48 extending around and registering with the edge of the disk 38 to achieve the desired flexibility, to avoid damage to the diaphragm by burrs at the edge of the disk, and to avoid extrusion of the rubber into the clearance space around the diaphragm.

Near the edge remote from the axis of the valve port 31 and on the side opposite the diaphragm, the disk 31] bears against a fulcrum element which may take the form of balls 43 seated in recesses in the cap 42 and spaced along a chord 48 (Fig. l) of the disk. The latter and its covering thus form a flapper 44 which is swingable toward and away from the seat 32 to close and open the valve 29 and thus permit or interrupt the flow of oil from the pump outlet to the passage 38.

During operation of the pump l3, the pressure created within the pump outlet is exerted on the diaphragm side of the valve flapper producing a resultant force tending to swing the flapper about the fulcrum 43 in the valve-opening direction. The magniture of this force is determined by the area of the flapper disk surrounding the valve seat 32 less the area of the small sector of the disk adjacent the fulcrum. This net area is sufficiently large to enable the fluid pressure actin thereon to overcome the opposing force of the spring 3! and hold the valve open when the pump outlet pressure is above a value desired to be maintained at the nozzle I0.

Herein the spring 3! is of the compression type acting at one end against the end of a plug 45 screw threaded into the cap 42 to enable the spring force and therefore the delivery pressure to be adjusted. At its inner end, the spring bears against a shouldered cup 46 connected to to a pin 4?, which is normal to the disk 30 and bears against the outer surface of the latter at a point offset from the fulcrum 43 and in this instance substantially alined with the axis of the valve 29.

The spring force acts continuously in opposiside of the diaphragm 40 over an area equal to the exposed area of the larger segment on one side of the chord 48 less the area of the smaller segment. When the resultant fluid pressure exceeds the force of the spring, the valve 29 will be held open and conversely, when, as by slowing down or stopping of the pump, the fluid pressure falls below the spring force, the flapper 44 will move against the seat and close the valve.

It will be observed, however, that the effective area on which the pressure fluid acts is smaller when the valve is closed than when the latter is open, the difference being the diaphragm area indicated at 49 (Fig. 4) which is covered by the tion to the fluid pressure acting on the opposite seat 32 when the valve is closed. As a result, when the motor is started, the pressure of the fluid delivered by the pump must, in order to overcome the spring 3!, build up to a value substantially higher than the pressure at which the flapper 44 will be held away from the seat 32 after the valve has been opened thus exposing the full area of the flapper. If, for example, the spring has been adjusted to allow the valve to open at a pressure of 125 p. s. i., the valve will, after opening, be held open at a substantially lower pressure, for example p. s. i. This substantial pressure differential is achieved by making the area which is initially efiective when the pump is started no more than .8 of the total area which is effective after the valve 29 has become open. Such a relationship will obtain in the valve construction above described if the diameter of the valve disk is '7 of an inch, the valve seat 32 is of an inch, and the fulcrum 48 is spaced 1% of an inch inwardly from the disk circumference.

The flapper above described may also be used as the movable member of an automatic by-pass valve 50 for maintaining the oil delivered to the nozzle at a substantially constant pressure after opening of the valve 29. To this end, a port 5! surrounded by a seat 52 is formed in the plug 35 for coaction with a portion of the diaphragm surface within the seat 32 of the main cut-off valve. The port 5| is at the end of a hole extending through the plug 35 and communicating through a passage '53 leading to the filter chamber and therefore to the pump inlet. The seat 52 is substantially flush with the seat 32 of the cut-off valve 29 so that when the latter is open, the bypass valve 50 will be opened to a degree determined by the fluid pressure in the recess 34 relative to the spring force. Part of the fluid delivered by the pump will thus be by-passed out of the recess 34 through the valve 50, the amount of this fluid increasing and decreasing progressively as the pressure in the recess increases and decreases. The equilibrium pressure thus established and maintained automatically will be determined by the adjustment of the force of the spring 31. When the pressure in the pump outlet falls after the driving motor has been deenergized, both of the valves 29 and 50 become closed.

The automatic differentially acting valve above described coacts with the by-pass valve 54 which, after initial adjustment, remains of fixed size and operates continuously to permit the escape of fluid from the pump outlet to a passage 54 leading to the return passage 53. The valve comprises a port 55 in the by-passage cooperating with the tapered end of a screw 56 to form a needle valve 51 which, by turning of the screw from the exterior of the casirng 26, may be adjusted to vary the size of the restriction. The adjustment of the latter is such that the rate of flow therethrough is somewhat less than the rate of fuel delivery by the pump at full speed less the capacity of the nozzle. For example, if the pump is capable of delivering 20 gallons per hour at 100 p. s. i. when the motor is operating at a full speed of 1750 R. P. M., the needle valve might, for use with a one gallon an hour nozzle, be adjusted to by-pass 16% gallons per hour at the same pressure leaving 2% gallons per hour to flow through the pressure regulating valve 50.

The operation of the combined pump and valve unit is as follows, assuming that the parts are sized and adjusted as described above. When 'valve'50 in the manner described above.

the motor 12 is started, all of'the fluid initially delivered by the pump will escape through the by-pass valve 51, and the valve member -44, owing to its smaller effective area at this time, does not open when the normal 100 p. s. i. operating pressure is attained in the pump outlet. Instead, the valve remains closed until a pressure of 125 p. s. i has actually built up in the pump outlet.

This does not occur until the motor is approaching its maximumoperating speed and has attained at speed of 165013.. F. M. at whichspeed the blower ll, whose efficiency is poor at low speeds, will deliver air at the proper rate to sup- .port efficient combustion when the fuel is first admitted to the nozzle by opening of the valve 29.

As soon as the valve 29 opens, the effective pressure area on the disk is increased by one fourth so that the valve will now remain open until, by the flow of fluid to the nozzle and escape through the by-pass outlet 5| the pressure in the chamber 34 has fallen to 100 p. s. i. at which the pressure remains constant by the action of the regulating At this lower pressure, the proportion of the fluid delivered by the pump and bleeding out through the fixed orifice is correspondingly reduced. Thus, when equilibrium at the operating pressure is attained with the valve 29 open, 16% gallons of the 20 gallons delivered by the pump will escape through the valve 51 while one gallon will flow through the nozzle l0 and the remaining 2% gallons will escape through the pressure regulating valve 50. This compares with the 18% gallons per minute which escapes through the valve 51 just before the valve '29 opens when the pressure in the chamber 34 is 125p. s. i. and the motor is operating at 1650 R. P. M. Because of the reduction in the flow through the valve 51 resulting from the action of the differential areas on the valve disk 40, it is unnecessary to change the effective size of the bleed valve 51 after opening of the valve 29. The adjustment of the bleed valve thus remains fixed and at an opening such that nearly the full normal capacity of the pump will be by-passed out of the chamber before the valve 29 opens to start delivery of fluid to the nozzle. As a result of this joint action of the fixed capacity bleed valve 5'! and the differentially acting cut-01f valve 29, it is possible to delay the initial delivery of fuel to the nozzle long enough for the motor to attain nearly its full operating speed. Eflicient combustion of the fuel initially delivered from the nozzle is thus assured.

It will be observed from the foregoing that the desired delay above referred to is achieved by the action of the pressure fluid itself and this, without material complication of the valve structure. The necessity of utilizing a switch controlled solenoid and an associated electrical delay device as has been the practice heretofore is avoided, and the over-all cost of the oil burner is reduced correspondingly. At the same time, the valve 29 is opened quickly and closed sharply and only at times when the blower is delivering a volume of air adequate for combustion of all oil passing the nozzle. In addition, through the use of the valve construction and mounting as described above, the diaphragm 40 is protected against rupture and therefore the spring side of the flapper 44 may be exposed to atmospheric pressure through openings M and M instead of to the return line as has been the practice heretofore. The transmission of any pulsations to the oil tank and other parts is avoided, thus eliminating the cause ofthe humming which occurs in the operation of'most present day oil burners.

The arrangement of the valve '29 and the associated parts inthenovel manner-above described is utilized to advantage in achieving automatic priming of the pump upon restarting of the motor after replenishing'the oil supply following shutdown due to exhaustion of the supply. "For this purpose, the valve parts arepreferably arranged i'n'th'e lowerportio'n of the casing 26 as shownin --Figs. 1 to 3 with the chamber 34 disposed above the level of the seat ("of the valve 29. Upon exhaustion of the oil supply during operation of the burner, the valve 29 will become closed because the air pumped into the chamber fl may 'flow out through the bleed orifice 55 at a greater rate than oil and therefore ataa rate .greater than the capacity of the pump to deliver air-at the pressure required in the chamber 34 order'to effect opening of the valve 29. Such closure of the valve 29 takes place while thenozzle andthe passage 33 between-the latter and the valve-1s filled with oil. Now, when the oil supply isrestored and the pump restarted, theair within the chamber is first forced out through the .passage 54 and the by-pass orifice, and there is no possibility of air remaining trapped within the chamber 34. Such free venting of the pump outlet enables the pump-to remove allair from the system before the pressure'in -the chamber 34 has increased sufficiently to open the valve'29 inthe manner previously described. 7

The differential action above described of the valve 29 and the delay resulting from its'coaction' with the continuously open restriction 55 may be achieved with other valve constructions examples of which are shown in Figs. '7 and18 in which the same reference numbers are applied to some of the parts in common with the preferred constructiondescribed above. In the first modification, the main admission and cut-off valve 29 is formed by an annular seat 58 coacting with adisk 59 on the inner end of a plunger 60 which is slidable in a cylinderfil and urged toward'the seat by a spring 63 acting against an adjustable abutment 64 and disposed'in the valve-casing 62 to whichthepassages 28, 38, and 53 lead. The pump outlet passage 28 leads into the chamber 34 surrounding the inner end of the valve,

plunger whose area iscorrelated with the-spring force and the size of the seat 58 to provide pressure areas of the proper sizes to achieve the differential valve action above described.

Within the seat -58'i a port 65 substantially flush with theseat and cooperating with the disk 59 to form the by-pass valve 50. As before, the chamber 34 communicates continuously with the by-pass outlet through the bleed valve 51 formed by the adjustable needle '56 and the coacting port 55.

When the pump I3 is started, fluid will-bleed continuously out of the valve 51 and the valve 29 will be held closed by the spring 63 until the pump motor has achieved a-speed close to maximum-so as to produce in the chamber before the valve opens a pressure, for example 125 p. s. i., somewhat above the value at which oil is to be delivered continuously to the nozzle HI. -As soon as the valve 29 opens, the'entire end surface of the plunger 60 is'exposed to the pump outlet pressure, and, therefore, the plunger. is shifted back and forth to vary the opening of the by-pass valve 50 and thus maintain a constant but lower delivery pressure, for example p. s. i.,i at the outlet 38. During such'normal "operation of the unit, fluid continues to by-pass through the valve 57 but, owing to the lower pressure then prevailing in the chamber 34, the rate of bleed is lower than at the time of opening of the valve 29.

Now when the pump driving motor is deenergized, the escape of fluid through the valve 57 7 assists in causing a quick fall in the pressure in the chamber 34 sufliciently below the normal operating pressure to allow the valve member 60 to-move rapidly and close the valve 29. An extremely quick cut-off of the fuel flow to the nozzle is thus efiected.

In the form shown in Fig. 8, the valve controlling the flow of fluid delivered by the pump is divided into two parts interposed in series during acceleration of the pump and respectively operable at the high and low pressure values (125 p. s. i. and 100 p. s. i.) above referred to. In

this case, the pressure areas are formed on different movable valve elements 61 and 68 loaded by individual springs I2 and 19 which are adjusted in proper relation with respect to the two areas. Herein, the valve elements comprise plungers slidable in cylinders 69 and 10 in 2. casing H communicating with the various fluid passages 28, 38, and 53. The plunger 61 is urged inwardly by the spring 12 whose force is opposed by fluid pressure within a chamber 73 acting on the end surface 14 of the plunger which surface constitutes one of the pressure areas above referred to. The chamber communicates with the pump outlet 28, with the needle valve restriction 55,

" and with a. port 15 opening into the cylinder 10 and covered. by the plunger 58 when the main valve 29 is open.

Near its end 14, the valve cylinder 69 cooperates with a port 16 to form a pressure responsive valve 85 controlling the admission of fluid from the chamber 13 to a chamber Tl surrounding the inner end 18 of the plunger 68 which is urged by the spring 19 toward closed position in which a disk 80 on the plunger abuts against a seat 8| and cooperates with the latter to form the main valve 29. The by-pass or pressure regulating valve 50 is formed in this instance by coaction between a port 82 leading to the passage 53 and a groove 83 formed near the end and around the periphery of the plunger 68 and communicating with the chamber H through a hole 84. The spring 12 is correlated with the area 14 so that the plunger is maintained in the position shown in Fig. 3 and the valve 85 is closed at pressures in the chamber 15 below the valve, for example 125 p. s. i., at which it is desired to admit fluid to the burner nozzle by opening of the valve 29. Similarly, the spring 19 is adjusted to permit opening of the valve 29 at pressures in the chamber 11 above the desired nozzle operating pressure, for example 100 p. s. i., but to allow the valve to close at lower pressures. At the higher pressures in the chamber 11, the plunger 68 moves to bring the groove 83 into registry with the port 82 thus allowing fluid to by-pass back to the pump inlet so as to regulate the pressure of the fluid delivered to the nozzle passage 38.

In operation, let it be assumed that the parts are positioned as shown in Fig. 8 when the operation of the pump is started. All of the valves 29, 50, and 85 remain closed until the driving motor approaches its full speed and a pressure of 125 p. s. i. is attained in the chamber 73 in spite of the continuous escape of most of the delivered fluid through the restriction 55. In response to the attainment of such a high pressure, the

plunger 61 moves to open the valve and admit fluid at p. s. i. to the chamber 11. This pressure, acting on that area 18 of the plunger 68 which is exposed around the seat 8!, immediately overcomes the spring 18 and moves the plunger 68 to open the valve 29 and admit fluid to the nozzle l0. At the same time, one part of the groove 83 registers with the port 15 thereby admitting pressure fluid directly from the chamber 13 to the chamber 11 through the hole 84. Thus, even though the pressure in the chamber 11 may, after opening of the valve 29, fall below that required to maintain the valve 85 open, the valve 29 will remain open under the pressure of the fluid flowing from the chamber 11 through the port I5 and the hole 84.

After opening of the valve 29, a somewhat larger area of the end of the plunger 68 will be exposed to the fluid in the chamber Ti and the plunger will be moved far enough to bring the groove 83 into registry with the port 82 thus allowing fluid to escape until the desired lower pressure in the chamber T! has been achieved. Thereafter, the plunger moves back and forth to vary the by-pass opening and thus maintain the delivery of fluid to the nozzle at the desired constant pressure. During this operation, the valve 85 remains closed and fluid from the pump flows to the valve 29 through the hole 84 in the plunger 68.

When the pump motor is deenergized, the pressure in the chamber T! is reduced quickly not only by slowing down of the pump, but also by the continued bleeding of fluid out of the chamber I3 through the restriction 55. A sharp closure of the valve 29 and cut-off of the fluid flow to the nozzle is thus effected.

The combined pressure regulating and cut-off valve as shown in Figs. 2 and 3 forms per se the subject matter of my co-pending application Serial No. 85,445, filed April 4, 1949.

I claim as my invention:

1. The combination of, a fluid pump having an inlet and an outlet, an electric motor for driving said pump, a valve controlling the flow of fluid out of said outlet, a member for actuating said valve movable between valve-open and valveclosed positions, means yieldably urging said member toward said valve-closed position, said member having a pressure area acted on by the fluid in said outlet to urge the member toward said open position in opposition to said yieldable means, an additional pressure area on said member exposed to the fluid in said outlet when the valve is open to substantially increase the force opposing said yieldable means, and means defining a restricted by-passage communicating with said pump outlet and permitting the continuous escape of fluid out of said outlet during operation of said pump within a low speed range of operation of said motor, said by-passage remaining open in the continued operation of said pump and acting to limit the rate of by-pass sufliciently to permit the outlet pressure acting on said first area to overcome said yieldable means and cause the valve opening movement of said member when the motor has attained a predetermined higher speed.

2. The combination of, a rotary fluid pump having an inlet and outlet and adapted to be driven at a predetermined speed, a valve controlling the flow of fluid out of said outlet, a member for actuating said valve movable between valveopen and valve-closed positions, spring means yieldably urging said member toward said valve 9 closed position, said member having a pressure area acted on by the fluid in said outlet to urge the member toward said open position in opposition to said spring means, an additional pressure area on said member of substantial size as compared to said first area exposed to the fluid in said outlet when the valve is open whereby to increase the force opposing said spring means, and means defining a restriction continuously communicating with said pump outlet and icy-passing fluid out of said outlet during starting of said pump and thereafter limiting the rate of by-pass sui'ficiently to permit the pressure in said outlet acting on said first area to overcome said spring means and cause the valve opening movement of said member when the pump has attained a speed more than half of said predetermined speed.

3. In a fluid distributing system, the combination of a rotary pump adapted to be driven at a predetermined speed and deliver fluid at a pressure which increases progressively as the pump speed increases, a passage for conveying fluid delivered by the pump to a point of use, a valve controlling the flow of said fluid through said passage including a member movable between valveopen and valve-closed positions, loading means constantly urging said member toward valveclosed position, a pressure area on said member exposed to the fluid in said outlet and acted on thereby when said valve is closed to produce a force opposed to said loading means and capable of overcoming the latter at a predetermined outlet pressure corresponding to a pump speed less than but more than half of said predetermined speed, the effective area of said member being increased in size automatically as an incident to opening of said valve whereby to hold the member in valve open position at an outlet pressure at least twenty per cent lower than said predetermined pressure, a restricted by-passage communicating with said pump outlet and adjusted to pass fluid when said valve is both open and closed at a fixed rate less than the rate of delivery of the fluid by said pump at said predetermined pressure and said predetermined speed, and a by-pass valve rendered active in response to opening of said first valve and operable to release the excess fluid automatically from said outlet and maintain said lower pressure substantially constant during the continued operation of said pump.

4. In a fluid distributing system, the combination of a rotary pump adapted to attain a predetermined speed progressively after starting and deliver fluid at a given maximum rate, a passage for conveying fluid delivered by th pump to a point of use, a valve controlling the admission of said fluid to said passage and yieldably urged toward closed position, actuating means for opening said valve including an area exposed to the pump outlet pressure when said valve is closed to produce a force sufiicient to open said valve when a predetermined outlet pressure is attained, said actuating means having an area exposed to the pump outlet pressure and of greater effectiveness on said valve than said first area when the valve is open and operable to hold said valve open at an outlet pressure lower than said predetermined value, and a continuously open by-pass restriction communicating with said pump outlet and operable at said higher pressure to release fluid at a rate approaching but less than said maximum rate of delivery of fluid by said pump at said predetermined speed.

5, In a fluid distributing system, the combinetion of, a fluid chamber, an outlet valve therefor, a rotary pump adapted to be driven at a predetermined speed and operable at such speed to deliver fluid into said chamber at a predetermined rate, an automatic pressure responsive valve operable when said outlet valve is open to by-pass fluid out of said chamber and maintain the pressure therein at a predetermined value, an actuator for said outlet valve operated differentially in response to changes in said chamber and operable to hold the valve open at said predetermined pressure value but to maintain the valve closed during acceleration of said pump until the pressure in said chamber has reached a value at least twenty per cent higher than said predetermined value, and an adjustable bleed outlet leading from said chamber and dimensioned to pass all of the fluid delivered by said pump until said higher pressure has been attained in said chamber and, after said outlet valve has become opened, to pass out of the chamber the major portion of the fluid delivered by the pump.

6. In a fluid distributing system, the combination of, a fluid chamber, an outlet valve therefor, a rotary pump adapted to be driven at a predetermined speed to deliver fluid, an automatic pressure responsive valve operable when said outlet valve is open to by-pass fluid out of said chamber and maintain the pressure therein at a predetermined value, an actuator for said outlet valve operated in response to changes in said chamber to hold the valve open at said predetermined pressure value, an adjustable bleed outlet leading from said chamber and dimensioned to pass the major portion of the fluid delivered by said pump, a third valve controlling the flow of fluid from said pump outlet to said chamber, and means responsive to the pump outlet pressure and operable during acceleration of the pump to maintain said third valve closed until the outlet pressure has attained a predetermined value substantially higher than said predetermined pressure value.

7. In a fluid distributing system, the combination of, a fluid chamber, an outlet valve therefor, a rotary pump adapted to be driven at a predetermined speed and operable at such speed to deliver fluid into said chamber at a predetermined rate, an automatic pressure responsive valve operable when said outlet valve is open to by-pass fluid out of said chamber and maintain the pressure therein at a predetermined value, an adjustable bleed outlet from said chamber dimensioned to pass the major portion of the fluid delivered by said pump at said predetermined speed and pressure and remaining of constant size while said outlet valve is both open and closed, and an actuator for said outlet valve operated differentially in response to changes in said chamber and operable to hold the valve open at said predetermined pressure value but to maintain the valve closed during acceleration of said pump until the speed of the latter is near said predetermined speed.

GUNNAR A. WAHLMARK.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,868,651 Wood July 26, 1932 1,931,543 High Oct. 24, 1933 2,184,133 Wahlmark Dec. 19, 1939 2,350,502 Garday June 6, 1944 

